341
FXUS65 KBYZ 251118
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
518 AM MDT MON MAY 25 2026
KEY MESSAGES
- VERY WARM TEMPERATURES MONDAY & TUESDAY WILL ENHANCE MOUNTAIN
SNOWMELT AND INCREASE RIVER FLOWS. NO FLOODING IS EXPECTED AT
THIS TIME. SOME DAILY MAX TEMPERATURE RECORDS MAY BE BROKEN.
- ISOLATED AFTERNOON & EVENING THUNDERSTORMS OVER THE WEST ON
MONDAY WILL BE CAPABLE OF PRODUCING ERRATIC AND GUSTY WINDS.
- DAILY CHANCE OF SHOWERS AND THUNDERSTORMS TUESDAY THROUGH THE
END OF THE WEEK. STRONG TO SEVERE THUNDERSTORMS AND HEAVY RAIN
ARE POSSIBLE, BUT DETAILS REMAIN UNCERTAIN. TEMPERATURES WILL
REMAIN ABOVE NORMAL.
DISCUSSION
THROUGH NEXT SUNDAY...
EXPECT VERY WARM TEMPERATURES TODAY & TUESDAY UNDERNEATH A RIDGE
ALOFT WITH FLOW BACKING TO THE SW THEN S. LOOK FOR HIGHS IN THE
MID 80S TO MID 90S, WARMEST IN THE EAST ON TUESDAY. SOME DAILY
RECORD HIGHS WILL BE APPROACHED OR BROKEN. THE STRETCH OF HOT DAYS
(AND WARMER NIGHTS) WILL ENHANCE MOUNTAIN SNOW MELT AND INCREASE
FLOWS ON RIVERS AND STREAMS.
T-STORM POTENTIAL BEGINS TO INCREASE IN OUR WEST THIS AFTERNOON
AND EVENING. A LOW CURRENTLY OFF THE BC COAST WILL DROP TO THE
PACNW COAST OVER THE NEXT 24 HOURS, ALLOWING FOR AN INCREASE IN
MID LEVEL MOISTURE ADVECTING OUT OF THE GREAT BASIN. WE SHOULD SEE
CONVECTION BEGIN BY 19-20Z OVER THE BEARTOOTH-ABSAROKAS AND SPREAD
OVER WESTERN LOWER ELEVATIONS THRU AROUND SUNSET. AIR MASS REMAINS
RELATIVELY DRY TODAY AND STORMS WILL REMAIN WEAK BUT HIGH-BASED,
AND MAY PRODUCE ERRATIC WIND GUSTS TO 50 MPH.
ATMOSPHERIC MOISTURE INCREASES MUCH MORE AGGRESSIVELY TUESDAY AS
THE DIGGING LOW TO OUR WEST ALLOWS FOR A SURGE OF MOISTURE UP THE
HIGH PLAINS PER SE-S FLOW. ENSEMBLES CONTINUE TO SHOW PWATS UP TO
0.70-1.00". THUS, COVERAGE OF AFTERNOON & EVENING STORMS WILL
INCREASE TO SCATTERED OVER THE WEST HALF OF OUR CWA, AND THESE
STORMS WILL BE WETTER (THOUGH STILL FAIRLY HIGH-BASED). SHEAR IS
LACKING THIS FAR EAST HOWEVER, LIMITING SEVERE POTENTIAL (WHICH
WILL BE GREATER OVER WESTERN MT CLOSER TO THE LOW). MODEL
SOUNDINGS ARE SUGGESTIVE OF WET MICROBURSTS AND THIS WILL BE
SOMETHING TO MONITOR.
OVERALL PATTERN FAVORS A DAILY CHANCE OF THUNDERSTORMS THROUGH THE
END OF THE WEEK BUT THERE ARE STILL DETAILS TO BE WORKED OUT. A
FEW NOTES: (1) MODELS HAVE TRENDED FURTHER WEST WITH THE LOW,
PLACING IT OVER NV WEDNESDAY & THURSDAY BEFORE IT BEGINS TO EJECT
NORTHWARD. (2) A WEAK PV MAX OVER SOUTHERN CA IS EXPECTED TO DRIFT
EASTWARD THE NEXT COUPLE OF DAYS, REACHING THE SOUTHERN PLAINS
TUESDAY NIGHT/WEDNESDAY. IT APPEARS THAT THIS FEATURE WILL HELP TO
PRODUCE SHOWERS/T-STORMS OVER THE PLAINS TO OUR SOUTHEAST, TO AN
EXTENT LIMITING ADDITIONAL PLAINS MOISTURE ADVECTION THIS FAR
NORTH. THIS SEEMS TO BE THE REASON FOR MODELS SHOWING SLIGHT
MIDWEEK LOWERING OF PWATS. THE COMBINATION OF THE WESTWARD SHIFT
IN THE LOW AND THE WAVE OVER THE SOUTHERN PLAINS HAS RESULTED IN A
LOWER QPF SIGNAL FOR US AMONG ALL ENSEMBLES. NOT TO DOWNPLAY THE
ACTIVE WEATHER PATTERN, WE WILL STILL SEE CHANCES OF T-STORMS EACH
DAY, BUT OVERALL PRECIP LOOKS TO BE CONVECTIVELY DRIVEN ONLY W/O
A SYNOPTIC COMPONENT. (3) BULK SHEAR IS EXPECTED TO REMAIN ON THE
LOW SIDE THROUGH THURSDAY AND THIS WILL LIMIT SEVERE POTENTIAL.
IT NOW SEEMS THAT THE GREATEST POTENTIAL FOR WIDESPREAD SHOWERS
AND T-STORMS AND A HIGHER RISK OF SEVERE STORMS/HEAVY RAIN WILL BE
AT THE END OF THE WEEK (FRIDAY AND/OR SATURDAY) AS THE LOW KICKS
NORTHWARD THRU ID/WY/MT, PROVIDING STRONGER ASCENT AND GREATER
SHEAR. THERE ARE STILL MODEL UNCERTAINTIES HERE AND TIMING IS
DIFFICULT TO SAY.
AFTER THE VERY WARM START, WE SHOULD SEE SLIGHT COOLING (BUT STILL
WARMER THAN NORMAL) WEDNESDAY THROUGH FRIDAY. SATURDAY/SUNDAY
SHOULD BE POST-FRONTAL AND COOLER (70S?). CANNOT RULE OUT T-STORMS
THROUGH NEXT WEEKEND BUT THE PWATS SHOULD BE SOMEWHAT LOWER BY
THEN.
JKL
AVIATION
12Z TAF DISCUSSION...VFR CONDITIONS WILL PREVAIL FOR THE NEXT 24
HOURS. HIGH BASED ISOLATED WEAK SHOWERS/THUNDERSTORMS ARE EXPECTED
THIS AFTERNOON/EVENING FROM BILLINGS WEST INTO THE MOUNTAINS.
ERRATIC WIND GUSTS TO 40KTS WILL BE THE MAIN THREAT NEAR
CONVECTION. THOUGH PRECIPITATION MAY MAKE IT TO THE GROUND WITH
THIS ACTIVITY, IT SHOULDN'T DIMINISH FLIGHT CATEGORIES BELOW VFR.
CONVECTION IS FORECAST TO QUICKLY DIMINISH AROUND 02-03Z.
CONVECTIVE COVERAGE WAS ENOUGH TO ADD A PROB30 GROUP TO KLVM FOR
THE LATE AFTERNOON/EARLY EVENING HOURS. HRRR CONTINUES TO SHOW A
CELL MOVING THROUGH KBIL AROUND 00Z WITH GUSTS IN THE 35-40KT
RANGE, BUT COVERAGE/CONFIDENCE TOO LOW FOR A PROB30 JUST YET, BUT
SOMETHING TO BE AWARE OF. CHAMBERS
PRELIMINARY POINT TEMP/POPS
TDY TUE WED THU FRI SAT SUN
-------------------------------------------------------
BIL 090 057/093 060/088 060/091 061/090 058/080 053/081
1/U 22/T 42/T 22/T 11/U 34/T 32/T
LVM 086 049/084 050/080 050/085 052/080 047/070 044/073
2/T 26/T 57/T 32/T 24/T 46/T 23/T
HDN 090 053/094 059/089 059/091 059/091 056/081 051/081
0/U 21/B 32/T 22/T 12/T 34/T 32/T
MLS 092 061/096 067/092 064/090 062/089 059/082 053/081
0/U 00/N 21/N 11/N 11/U 34/T 32/W
4BQ 091 060/094 064/089 061/087 060/088 058/081 052/080
0/U 00/N 22/T 12/T 12/T 34/T 32/W
BHK 092 058/094 061/089 059/087 057/084 055/082 050/079
0/U 00/N 20/N 01/N 11/N 35/T 43/T
SHR 087 048/091 052/085 050/086 050/086 048/078 044/078
1/U 12/T 33/T 22/T 12/T 34/T 24/T
BYZ WATCHES/WARNINGS/ADVISORIES
MT...NONE.
WY...NONE.
WEATHER.GOV/BILLINGS
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